// SPDX-License-Identifier: GPL-2.0-only/* * Here's a sample kernel module showing the use of kprobes to dump a * stack trace and selected registers when kernel_clone() is called. * * For more information on theory of operation of kprobes, see * Documentation/trace/kprobes.rst * * You will see the trace data in /var/log/messages and on the console * whenever kernel_clone() is invoked to create a new process. */ #define pr_fmt(fmt) "%s: " fmt, __func__ #include <linux/kernel.h>#include <linux/module.h>#include <linux/kprobes.h> static char symbol[KSYM_NAME_LEN] = "kernel_clone";module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644); /* For each probe you need to allocate a kprobe structure */static struct kprobe kp = {	.symbol_name	= symbol,}; /* kprobe pre_handler: called just before the probed instruction is executed */static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs){#ifdef CONFIG_X86	pr_info("<%s> p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",		p->symbol_name, p->addr, regs->ip, regs->flags);#endif#ifdef CONFIG_PPC	pr_info("<%s> p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",		p->symbol_name, p->addr, regs->nip, regs->msr);#endif#ifdef CONFIG_MIPS	pr_info("<%s> p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",		p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);#endif#ifdef CONFIG_ARM64	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",		p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);#endif#ifdef CONFIG_ARM	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",		p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);#endif#ifdef CONFIG_RISCV	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",		p->symbol_name, p->addr, regs->epc, regs->status);#endif#ifdef CONFIG_S390	pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",		p->symbol_name, p->addr, regs->psw.addr, regs->flags);#endif#ifdef CONFIG_LOONGARCH	pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",		p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);#endif 	/* A dump_stack() here will give a stack backtrace */	return 0;} /* kprobe post_handler: called after the probed instruction is executed */static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,				unsigned long flags){#ifdef CONFIG_X86	pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",		p->symbol_name, p->addr, regs->flags);#endif#ifdef CONFIG_PPC	pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",		p->symbol_name, p->addr, regs->msr);#endif#ifdef CONFIG_MIPS	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",		p->symbol_name, p->addr, regs->cp0_status);#endif#ifdef CONFIG_ARM64	pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",		p->symbol_name, p->addr, (long)regs->pstate);#endif#ifdef CONFIG_ARM	pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",		p->symbol_name, p->addr, (long)regs->ARM_cpsr);#endif#ifdef CONFIG_RISCV	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",		p->symbol_name, p->addr, regs->status);#endif#ifdef CONFIG_S390	pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",		p->symbol_name, p->addr, regs->flags);#endif#ifdef CONFIG_LOONGARCH	pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",		p->symbol_name, p->addr, regs->csr_estat);#endif} static int __init kprobe_init(void){	int ret;	kp.pre_handler = handler_pre;	kp.post_handler = handler_post; 	ret = register_kprobe(&kp);	if (ret < 0) {		pr_err("register_kprobe failed, returned %d\n", ret);		return ret;	}	pr_info("Planted kprobe at %p\n", kp.addr);	return 0;} static void __exit kprobe_exit(void){	unregister_kprobe(&kp);	pr_info("kprobe at %p unregistered\n", kp.addr);} module_init(kprobe_init)module_exit(kprobe_exit)MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");MODULE_LICENSE("GPL");